In a classic study of blood types in Italy, Dr. Luigi Cavalli-Sforza (1969) foun
ID: 60606 • Letter: I
Question
In a classic study of blood types in Italy, Dr. Luigi Cavalli-Sforza (1969) found that small, isolated towns in mountain regions had reduced genetic diversity within the populations, but showed significant genetic differences from one town to the next. In valley regions with more movement of people from place to place, he found more diversity within the population of any given town, and fewer differences between towns. If you consider your genetic simulation to represent one mountain town, and other lab groups to represent different mountain towns, can you explain Cavallis results? How could you alter this lab procedure to simulate what happens in valley towns?
Explanation / Answer
In small towns, migration of people from one town to another is negligible. This may be due to lack of transport facilities between the two towns. So, there is interbreeding between individuals of the same town. This results in lack of genetic diversity , within the same town. Individuals of different towns cannot interbreed with each other. So, as generations pass by, a significant genetic difference arises between the two groups, which are geographically isolated.
On the other hand, individuals living in valley towns, movement of people from one town to other takes place. So, they are not geographically isolated. Interbreeding and thus mixing of gene pool is possible between people of different valley towns. So, there is more crossing over and thus more genetic diversity.